1. Field of the Invention
The present invention relates to a light emitting device and a method for manufacturing the same. More particularly, the present invention relates to a light emitting device that has a p-type AlN/GaN layer of a super lattice structure between a p-type nitride semiconductor layer and an active layer, and to a method for manufacturing the same.
2. Description of the Related Art
Generally, nitride-based semiconductors are widely used in blue/green light emitting diodes or laser diodes for light sources of full-color displays, traffic lights, general lighting fixtures, optical communication devices, etc. The nitride-based semiconductor includes an active layer of a multi-quantum well structure disposed between n-type and p-type nitride semiconductor layers to emit light by recombination of electrons and holes in the active layer.
The nitride semiconductors are generally formed by metal-organic chemical vapor deposition. In the metal-organic chemical vapor deposition, an organic source gas containing group III metal is supplied into a reaction chamber, where a substrate is located, to grow a nitride semiconductor layer on the substrate.
The p-type nitride semiconductor layer includes p-AlGaN as an electronic blocking layer (EBL) and is doped with Mg, which is combined with hydrogen, deteriorating crystallinity of the p-type nitride semiconductor layer while deteriorating electrical conductivity of the p-type nitride semiconductor layer. The use of Mg as a dopant results in an increase of current leakage, deterioration of reverse voltage characteristics, and lower current diffusion of the light emitting device, which decreases luminescence efficiency and brightness of the light emitting device.
To lower driving voltage of a GaN-based semiconductor light emitting device while improving output thereof, it is necessary to improve the electrical conductivity of the p-type nitride semiconductor layer. However, an increase in doping concentration of Mg causes a decrease of carrier concentration, what is referred to as the self-compensation phenomenon.
Therefore, there is a need to improve electrical conductivity and crystallinity of the p-type semiconductor layer by sufficiently increasing the doping concentration of Mg.